What is ndisuio?

Ndisuio.sys is a Windows driver. A driver is a small software program that allows your computer to communicate with hardware or connected devices. This means that a driver has direct access to the internals of the operating system, hardware etc. The free file information forum can help you determine if ndisuio.sys is a Windows system file or if it belongs to an application that you can trust.

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Ndisuio.sys file information

The process known as NDIS User mode I/O Driver or NDIS User mode I/O driver belongs to software Microsoft Windows Operating System or Betriebssystem Microsoft Windows by Microsoft (

Description: Ndisuio.sys is an important part of Windows, but often causes problems. Ndisuio.sys is located in the C:\Windows\System32\drivers folder. Known file sizes on Windows 10/8/7/XP are 12,928 bytes (37% of all occurrences), 14,592 bytes or 16,896 bytes. 
The driver can be started or stopped from Services in the Control Panel or by other programs. The program has no visible window. Ndisuio.sys is a trustworthy file from Microsoft. Ndisuio.sys is a Windows core system file. ndisuio.sys appears to be a compressed file. Therefore the technical security rating is 0% dangerous, however you should also read the user reviews.

Recommended: Identify ndisuio.sys related errors

Important: Some malware disguises itself as ndisuio.sys, particularly when not located in the C:\Windows\System32\drivers folder. Therefore, you should check the ndisuio.sys process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

You don't need this running unless your wireless devices don't work without it. So, turn it off, as it seems to send and recieve and take up bandwidth.....and you don't even know what it's sending and receiving! Isn't it funny that Microsoft doesn't tell you.
  Randy Holmes  
its a windows app
It's the wireless config driver. It's not necessary, but helps some wireless cards work better.
  Owen J  
ndisuio.sys will duplicate itself when deleted from the system file driver cache, it will also not disable when wireless services are disabled under admin tools/services. Sygate is constantly blocking it, which is a good thing, leading me to believe it is not at all essential for xp functionality at my level of pc use. Side note sygate was bought out by symantec (sic) coporate conspiracy theory abounds. This little humdinger is nothing but trouble. Why would a system routine be impervious to user disabling? I have yet to experiment with wireless apps, I dont do wireless.
I Am having serious start up problems, and startup stops at the DOS blackboard (during start up) and reads: "trying to install MS_NDISUIO . And there it sits for some time. If I get out of this window, it eventually takes me to recover Manager...then Start up Recovery...which does it's little dance then tells me that Start up Repair cannot repair the computer.
  Sue Leef.  

Rating chart

Summary: Average user rating of ndisuio.sys: based on 11 votes with 5 user comments. 3 users think ndisuio.sys is essential for Windows or an installed application. 2 users think it's probably harmless. One user thinks it's neither essential nor dangerous. 2 users suspect danger. 3 users think ndisuio.sys is dangerous and recommend removing it. One user is not sure about it.

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Best practices for resolving ndisuio issues

A clean and tidy computer is the key requirement for avoiding problems with ndisuio. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the ndisuio.sys process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

ndisuio.sys [all]